It's not being indecent. The father didn't know what it was and I'm sure the kid was freaking out as well. And I don't think this should be a FML because it's the OPs job to look at this type of medical stuff and help them understand what it is.

That is not child porn #3, at least not in that context, sorry you had to see that OP. I do have to say it's good training though because his child was probably very young and he was the standard overly concerned father trying to help his baby (and make his wife happy) one day when your child encounters that same god awful rash, you'll know exactly how to handle it. life lesson.

I'm agreeing here. It "could" look bad if someone wanted to "get" him and showed the pic to the police, but it would probably blow over when they saw most pics were of the kid dressed as some minecraft character, his spouse's cooking fails, cat's antics, etc.